This section introduces aspects that may facilitate a better understanding of the disclosure. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.
Mobile broadband continues to drive a demand for a higher overall traffic capacity and a higher achievable end-user data rate in a radio access network. Several application scenarios in the future will require data rates up to 10 Gbps in local areas. The demand for such a high system capacity and end-user date rates may be met by networks in which a distance between access nodes, ANs, ranges from a few meters in indoor deployments up to roughly 50 m in outdoor deployments, i.e. with an infra-structure density considerably higher than the densest networks of today. The broad transmission bandwidth required for providing a data rate up to 10 Gbps and above may promisingly be obtained from mmW bands.
In a traditional 3GPP LTE (3rd generation partnership project long term evolution) system, when a user equipment UE within coverage of an eNB, which may be referred to as a source eNB, moves to coverage of another eNB, which may be referred to as a target eNB, a handover procedure needs to be executed. During the handover procedure, the UE's context information and packets that the UE needs to transmit/receive will be forwarded from the source eNB to the target eNB to guarantee a lossless and seamless handover.
FIG. 1 schematically illustrates the handover procedure in the 3GPP LTE system. Firstly, a UE sends a measurement report to a source eNB (S_eNB). Then the S_eNB will prepare for handover to a target eNB (T_eNB) by transferring to the T_eNB information required for the handover. The required information may comprise the UE's context information including UE-AMBR (Aggregate Maximum Bit Rate), UE Security Capability, KeNB*, E-RAB (E-UTRAN Radio Access Bearer) to be setup, RRC (Radio Resource Control) Context, UE History information etc. and may also comprise SN (Sequence Number) Status Transfer and packets to be transferred in downlink (DL) or uplink (UL) etc. Upon reception of the information required for the handover from S_eNB to T_eNB, the T_eNB may proceed to complete the handover procedure as illustrated in FIG. 1. Apparently, this handover procedure puts a very heavy burden on the source eNB, since all information required for handover needs to be maintained at the source eNB and forwarded to the target eNB from the source eNB. Accordingly, the complexity of eNBs and the cost for deploying eNBs in the LTE system are relatively high. Considering the much higher density of AN deployment in mmW networks, application of the existing handover procedure of the LTE system to the mmW networks unavoidably pushes the cost and system complexity further higher.
Therefore, there is a need for a solution specifically designed for mobility management in mmW networks that is adapted to inherent characteristics of the mmW networks.